1. Technical Field
The present invention relates to a heat exchanger which exchanges heat with cooling liquid, and a projector including the heat exchanger.
2. Related Art
Currently, such a projector is known which includes a circulation type liquid-cooling device for circulating cooling liquid along a flow path and cooling a cooling target such as a liquid crystal panel by the circulated cooling liquid so as to efficiently cool the cooling target.
According to this type of liquid-cooling device, a heat exchanger capable of lowering the temperature of the cooling liquid is often used to effectively cool the cooling target by the cooling liquid (for example, see JP-A-2006-259282).
More specifically, the heat exchanger disclosed in JP-A-2006-259282 has a hollow rectangular parallelepiped shape, and an inlet unit and an outlet unit through which cooling liquid flows in and out is formed on one side surface of the rectangular parallelepiped shape, respectively. The heat exchanger further contains channels along which the cooling liquid flows. The heat exchanger having this structure provides heat exchange between the cooling liquid and partition walls constituting the channels and lowers the temperature of the cooling liquid while the cooling liquid introduced into the heat exchanger is flowing along the channels.
According to the liquid-cooling device described above, bubbles are generated in the flow paths by evaporation of the cooling liquid after the use of the cooling liquid for years. These bubbles flow into the heat exchanger with the cooling liquid and accumulate therein. When almost the entire part of the interior of the heat exchanger is filled with the bubbles, the heat exchange efficiency between the cooling liquid and the heat exchanger decreases by the function of the bubbles as a heat insulation layer. In this case, the temperature of the cooling liquid is difficult to be lowered.
The heat exchanger shown in JP-A-2006-259282 is designed on the assumption that images are projected from a projector installed in a position recognized as the normal position which allows images to be projected substantially in the horizontal direction (position of the projector placed on an installation surface such as a desk). In other words, the heat exchanger is so designed as to prevent such a condition that almost the entire part of the interior of the heat exchanger is filled with bubbles when the projector is placed in the normal position.
However, when the projector is placed in an upward projection position for projecting images upward (that is, a projection lens is disposed on the upper side) or in a downward projection position for projecting images downward (that is, the projection lens is disposed on the lower side), there is still a possibility that bubbles spread over almost the entire part of the interior of the heat exchanger.
More specifically, according to the heat exchanger disclosed in JP-A-2006-259282, each of the one side surface of the rectangular parallelepiped shape having the inlet unit and the one side surface of the rectangular parallelepiped shape having the outlet unit crosses the projection direction substantially at right angles, and the inlet unit and the outlet unit are disposed in parallel with the projection direction. Thus, when the projector is placed in the upward projection position or the downward projection position, there is a possibility that the inlet unit of the heat exchanger comes to the upper side. In this case, the outlet unit lies on the lower side.
When the heat exchanger is positioned in this condition, the bubbles having entered the interior of the heat exchanger with the cooling liquid move toward the upper space in the interior of the heat exchanger. These bubbles sequentially accumulate from the upper area toward the outlet unit formed in the lower area. Finally, the bubbles spread over almost the entire part of the interior of the heat exchanger.
Therefore, such a technology has been demanded which can maintain stable heat exchange efficiency between cooling liquid and the heat exchanger while preventing spread of bubbles over almost the entire part of the interior of the heat exchanger disposed in any positions.